Plan i meter



linirrnn Sfrnrns Parana @innen EUGENE HIG GINS, OF LANSNG, MICHIGAN.

PLANIMETER.

SPECIFICATION forming part of Letters Patent No. 301,594, dated July 8, 1884.

Application led March 26, 1884. (No model.)

To all whom, it .may concern:

Be it known that I, EUGENE HIGGINS, of Lansing, in the county of Ingham and State of Michigan, have invented new and useful Improvements in Planimeters; and l hereby .declare that the following is a full, clear, and

adapt it to giveonly direct readings, so as to facilitate its use by persons adverse to the use of more complicated instruments, which, although their scope is generally more exten ded, require certain calculation to arrive at the resultssonght for, and are therefore liable to confuse. My improved planimeter is especially adapted toiorm a measuring device for indicater-diagrams, and facilitate certain graphical methods in connection therewith-as, for instance, ascertaining the mean pressure of a given indicatordiagram, all as hereinafter more fully described and shown.

Inv the drawings which accompany this speciiication, Figure l is a plan view of my device complet-e. Fig. 2 is a side elevation of the guide-frame detached. Fig. 3 is a Vside elevation ci' the tracenleg detached.

A. is the guide-frame, which consists of the round guide-bar a, held upon its ends in the standards b D, formed by the upturned ends of the dat bar c. This latter bar is provided upon its under side with two or more steel pins, d, by means of which it can be firmly secured in place on a table or drawing-board.

.B is a crosshead sleeved upon the guidebar u.. It is provided with two cheeks, e e, adjustably or integrally secured thereto.

C is the tracer-leg, provided at the inn er end with the head j, and upon its outer end with the tracer-point I).

Gr is a bend or curve in the inner portion of the tracer-le.

h h are screw-pivots, by means of which the head of the traccrleg is pivotally secured between the cheeks c.

E is the measuring-wheel, secured upon an arbor, one end of which is journaled in a lug, j', cast on the tracer-leg, while the opposite end'is journaledin thehead f. To secure the utmost delicacyT of the instrument it is necessary to journal the arbor 'L' between steel points, or in any other suitable way for mounting the arbors of delicate mechanism. The measuring-wheel E is provided with two faces. The one of smaller diameter has a scale, 7c, registering with a lined indeX, Z, provided with a Zero-mark, and, if desired,with a vernier. The other face of the measuring-wheel is merely a rim, o, either plain or milled, but of a largerl diameter than the/face bearing the scale. The axis of the arbor z' should be in a vertical plane passing through the pivots h and the tracer-point D.

As the instrument is designed to give direct readings, the scale k must be constructed with that end in view but as the theory involved is well understood byscholars in mathematics l abstain from giving the modus operandi of constructing this scale.

The application of the instrument is similar to other instruments of the kind, and is as follows: 'Suppose we want to rind thelarea of an indicator-diagram. .Place the parts in posi! tionupon a table or drawing-board, as shown in Fi g. 1. Then begin to trace once completely around the diagram, following closely the outline. thereof, and taking care that the tracerwheel will come in contact with the face of the indicator-card or other plane surface placed underneath it', so that it will readily travel by friction al contact therewith. Now, if at the beginning of the tracing the measuring-wheel E has been so adjusted that the zero-mark of its scale registers with the fixed index or zeroinark, the iinal reading of the scale after the tracing of the indicator-diagram is completed will give the superficial contents of the diagram. Ifwe now put the tracing-p oint upon the point fm., which is in the atmospheric or in the vacuum line, and adjust the tracing-wheel so that the reading corresponds with the reading obtained by tracing the outline ofthe diagram, then trace perpendieularly upward until the zero-mark on the tracing-wheel corresponds with the fixed Zero-mark,we obtain a point, n. The distance m a multiplied by the scale of the diagram equals the mean effective pressure in pounds per square inch.

IOO

To obtain great exactitude it is necessary that the diagram and instrument be placed in' the proper relative positions to obtain at all .times a free and easy travel of the measuring- Wheel; but a little familiarity With the instrument by practice Will easily teach the operator.

The instrument can be put to a variety of other uses, especially for graphical demonstrations, which it has in common with other planimeters, but which in many cases are simplied by the fact of its giving direct readings of the superiicial contents.

To adapt the instrument to be stowed in a small compass I make the guide-bar a so that it may be removed from lthe standards b, and

free the cross-head B from its engagement.

W'hat I claim as my invention isl. In a planimete'r, the combination of the following parts: a rectilinear guide-frame proround guide-bar a, standards b, bar c, and pins y d, all arranged and combined substantially as described.

EUGENE HIGGINS.

Witnesses:

S. E. J AEvIs, W. T. HEBBARD. 

